A male whom is a temporary replacement for a male role for only a semesters length in a girls life. Needs certain attributes in order to keep the fling going and exciting. No strings attached unless otherwise clarified. it has to be very clear that the girl is using him for a placeholder until she finds Mr. right.

Kate: I'm hanging out with Kevin, and hes a lot of fun but i dont want anything serious so im going to make him my semester boyfriend.
Maria: Thats what i did last semester, works out for the best.